Device and method for compensating for displacement variations between dissimilar gear shifting levers and derailleurs on a bicycle

ABSTRACT

A device and method of mechanically synchronizing the displacement requirements of a bicycle derailleur with the displacement created by an indexing gear shifter lever. The device includes a linkage element that is mounted to a bicycle between a gear shifter lever and a derailleur. The linkage element is mounted to the bicycle with a pivot hinge, wherein the linkage element is free to rotate about the pivot hinge. A cable from the gear shifter lever is attached to the linkage element at a first distance from the pivot hinge. A cable from the derailleur is attached to the linkage element at a second different distance from the pivot hinge. As the cable from the gear shifter is moved, the linkage element is rotated and that movement is transferred to the cable for the derailleur in a compensated manner.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to the systems on bicycles used toshift between gears, wherein such systems include index-type gearshifter levers and derailleur assemblies that are interconnected bycables. More particularly, the present invention relates to devices thatcan adapt the use of a set of indexing gear shifter levers withdissimilar derailleur assemblies on a custom built bicycle.

[0003] 2. Prior Art Statement

[0004] Many bicycles contain a drive mechanism that has multiple gears.By shifting the bicycle's chain between the gears, the mechanicaladvantage between the pedals and the rear wheel of the bicycle can beselectively altered. Traditionally, the mechanism used to shift thebicycle's chain between different gears contains three interconnectedassemblies. These assemblies are the gear shifter levers, thederailleurs and the cables that extend between the gear shifter leversand the derailleurs. The gear shifter levers are the levers that arepositioned on or near the handlebars of the bicycle. These levers aremoved by the person riding the bicycle, thereby providing manualshifting control to rider. The derailleurs are the mechanism that guidethe bicycle chain onto different gears and compensate for slack in thechain as the chain moves between gears of different diameters. Thecables are the elements that interconnect the shifter levers and thederailleurs and transfer mechanical movement between the gear shifterlevers and the derailleurs. The cable is a direct mechanical drive.Consequently, if a gear shifter lever is used to move a cable ⅝^(th) ofan inch, the cable transfers that ⅝^(th) of an inch of movement directlyto a derailleur.

[0005] Because cables directly interconnect the gear shifter levers andthe derailleurs, the gear shifter levers and the derailleurs must becoordinated into matched sets. For example, if an indexing-type gearshifting lever is designed to shift gears for every ¼ inch of movementit causes in a cable, a derailleur must also be designed to shift gearsfor ever ¼ inch of movement it receives from the cable. If the gearshifter levers and the derailleurs are not coordinated, movement of thegear shifter levers between gears will not correspond to the properderailleur movement required to shift gears. The result is that thedesired gear shifting will not occur or may only partially occur,thereby creating chain slippage or chain chatter between gears.

[0006] Many bicycling enthusiasts customize their bicycles. Often gearshifter levers of a first type are desired to be used with derailleursof a second type. However, since the gear shifter levers and thederailleurs are not compatible, the two assemblies cannot be usedtogether. In the prior art, devices have been designed that mechanicallyalter the movement of a cable between a gear shifter lever and aderailleur. Such prior art devices are exemplified by U.S. Pat. No.5,447,475 to Socard, entitled Device And Process For synchronous ControlOf Bicycle Derailleurs. However, such prior art devices are intended toconvert the movement of one cable into two cables, or visa versa. Suchprior art systems do not enable dissimilar gear shifter levers andderailleurs to be used.

[0007] A need therefore exists for a device and method that can enabledissimilar indexing shifting levers and derailleurs to be used on acustom bicycle. This need is met by the present invention as describedand claimed below.

SUMMARY OF THE INVENTION

[0008] The present invention is a device and method of mechanicallysynchronizing the displacement requirements of bicycle derailleurs withthe displacement created by index-type gear shifter levers. The deviceincludes a linkage element that is mounted to a bicycle between the gearshifter levers and the derailleurs. The linkage element is mounted tothe bicycle with a pivot hinge, wherein the linkage element is free torotate about the pivot hinge. A cable from each gear shifter lever isattached to a linkage element at a first distance from the pivot hinge.A cable from each derailleur is attached to a linkage element at asecond different distance from the pivot hinge. As the cable from onegear shifter is moved, a linkage element is rotated and that movement istransferred to the cable for one derailleur. However, since the cablefor the derailleur and the cable for the gear shifter lever connect tothe linkage element at different points, only a percentage of the gearshifter lever's movement is transferred to the derailleur through thecables. The result is that different gear shifter levers and derailleurscan be mechanically synchronized to work together on the same bicycle.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] For a better understanding of the present invention, reference ismade to the following description of an exemplary embodiment thereof,considered in conjunction with the accompanying drawings, in which:

[0010]FIG. 1 is a side view of a bicycle containing two cabledisplacement compensation devices;

[0011]FIG. 2 is an enlarged view of a cable displacement compensationdevice;

[0012]FIG. 3 is an alternate embodiment of a cable displacementcompensation device; and

[0013]FIG. 4 is another alternate embodiment of a cable displacementcompensation device.

DETAILED DESCRIPTION OF THE INVENTION

[0014] Although the present invention cable displacement compensationdevice can be used in any cable control system, the cable displacementcompensation device is particularly well suited to use on a bicycle. Assuch, the present invention cable displacement compensation device willbe described in an application where it is applied to a bicycle, inorder to set forth the best mode contemplated for the invention.

[0015] Referring to FIG. 1, a bicycle 10 is shown. The bicycle 10 hasgear shifter levers 12, 13 positioned near the handlebars. It is thesegear shifter levers 12, 13 that are manually moved by a person ridingthe bicycle 10 in order to selectively change the gear ratio of thebicycle 10. Two derailleur assemblies 14, 16 are present on the bicycle10. The first derailleur assembly 14 is present over the chain wheelgears 18 that are affixed to the bicycle pedals 20. It is the functionof the first derailleur assembly 14 to move the bicycle chain 22 betweenthe different chain wheels 18 that are present. The second derailleurassembly 16 is present near the freewheel gears 24 on the rear wheel 26of the bicycle 10. It is the function of the second derailleur assembly16 to move the bicycle chain 22 between the different freewheel gears 24that are present, while eliminating slack in the chain 22 as it movesbetween gears of differing diameters. The structures of such derailleurassemblies 14, 16 are well known in the prior art.

[0016] In the shown embodiment, the two derailleur assemblies 14, 16 arenot designed to be used with the shifting levers 12, 13 present on thatsame bicycle 10. The derailleur assemblies 14, 16 are designed to shiftgears every time a cable displaces one of the derailleurs 14, 16 by apredetermined distance, e.g. {fraction (1/16)}^(th) of an inch. However,the gear shifter levers 12, 13 are designed differently and are intendedto cause a gear to shift upon a second displacement of a cable, e.g. ⅜inch. As such, the displacement created by the gear shifter levers 12,13 to create a gear change does not match the displacement needed by thederailleurs 14, 16 to create that gear change.

[0017] On the bicycle, two gear shifter levers 12, 13 are present. Onegear shifter lever 12 is intended to control the first derailleurassembly 14 and the other gear shifter lever 13 is intended to controlthe second derailleur assembly 16. A cable 30, 32 extends from each ofthe shifting levers 12, 13. However, the cables 30, 32 do not extenddirectly to the derailleur assemblies 14, 16. Rather, the two cables 30,32 extend to cable displacement compensation devices 40 that aredisposed on the bicycle 10 between the shifter levers 12, 13 and thederailleurs 14, 16.

[0018] Referring now to FIG. 2, it can be seen that a cable displacementcompensation device 40 is comprised of a linkage element 42 that isconnected to the frame of the bicycle 10 at a pivot joint 44. The pivotjoint 44 can be directly mated with the frame of the bicycle 10.However, in the shown embodiment, the pivot joint 44 connects to a clamp47 that can be selectively attached to the frame of the bicycle 10. Inthis manner, the cable displacement compensation device 40 can bemounted to a bicycle 10 without having to drill a hole in the frame ofthe bicycle 10.

[0019] The linkage element 42 is free to rotate about the pivot joint44. Two sets of holes are present on the linkage element 42. One set ofholes 46 is disposed upon the illustrated left edge of the linkageelement 42, while the second set of holes 48 is disposed upon theillustrated right edge of the linkage element 42. Holes 46, 48 from theleft edge set and the right edge set, respectively, are matched inpairs. Each pair of holes is a predetermined distance from the pivotjoint 44. It will be understood that as the linkage element 42 rotatesabout the pivot joint 44, the movement along an arcuate path for eachpair of holes differs. For any given rotational movement of the linkageelement, the holes more distant from the pivot joint 44 will travel afurther arcuate distance than will the holes closer to the pivot joint44.

[0020] Cable terminations 50 are provided. The cable terminations 50 aredesigned to engage the end of a cable and join that cable to one of theholes on the linkage element 42. Using the cable termination 50, a cablecan be selectively attached to any of the holes 46, 48 present on thelinkage element 42.

[0021] The cable displacement compensation device 40 is placed on thebicycle 10 at some point in between the shift levers 12, 13 (FIG. 1) andthe derailleurs 14, 16 (FIG. 1). Once a cable 52 from one of thederailleurs and a cable 32 from one of the gear shift levers areterminated with cable terminations 50, they are attached to the linkageelement 42 of the cable displacement compensation device 40 at differentpoints. In the shown embodiment, the cable 32 from the gear shifterlever is connected to a hole closer to the pivot joint 44 than is thecable 52 from the derailleur. As the gear shifter lever (FIG. 1) ismanually manipulated, the cable 32 from the gear shifter lever eitherpushes or pulls the linkage element 42. This causes the linkage element42 to rotate about the pivot joint 44. As the linkage element 42 movesabout the pivot joint 44, the linkage element 42 either pulls or pushesthe derailleur cable 52, thereby displacing that cable 52. Since theattachment point of the derailleur cable 52 is farther from theattachment point of the shifter cable 32, the displacement of thederailleur cable 52 differs from that of the shifter cable 32. If theshifter cable 32 is closer to the pivot joint 44 than is the derailleurcable 52, the derailleur cable 52 will be displaced farther than theshifter cable 32 for any movement of the linkage element 42. Forexample, if the shifter cable 32 is manually moved ⅛^(th) of an inch bya bicycle rider, such a displacement can result in a {fraction(3/16)}^(th) of an inch displacement in the derailleur cable 52.Alternatively, if the shifter cable 32 is farther from the pivot joint44 than is the derailleur cable 52, the derailleur cable 52 will bedisplaced less than the shifter cable 32 for any movement of the linkageelement 42. For example, if the shifter cable 32 is displaced {fraction(3/16)}^(th) of an inch by a bicycle rider, that displacement can resultin a ⅛^(th) inch displacement in the derailleur cable 52.

[0022] The variation in displacement between the shifter cable 32 andthe derailleur cable 52 can be selectively controlled by the placementof these cables in the holes in the lever linkage element 42. Thefarther the attachment points are from each other, the larger thedifferences in displacement. Conversely, the closer the attachmentpoints on the linkage element 42, the less disparity in displacementwill occur.

[0023] Thus, by using the cable displacement compensation device 40, agear shifter lever (FIG. 1) that is calibrated with one displacement tochange gears can be used with derailleurs (FIG. 1) that are calibratedwith a different displacement to change gears.

[0024] Referring to FIG. 3, an alternate embodiment of the cabledisplacement compensation device 60 is shown. In this embodiment, cableterminations 62 are directly coupled to a linkage element 64 atdifferent points. As such, the raw ends of cables need not be terminatedprior to attachment to the device. Furthermore, the cable terminations62 on the linkage element 64 are not linearly aligned. This isillustrated to point out that the linkage element 64 can have anyconfiguration and the cable connection points on the linkage element 64can be created in any pattern. Provided, that the holes in the linkageelement 64 are at varying distance from the pivot joint 66 around whichthe linkage element 64 rotates.

[0025] Also illustrated in FIG. 3 is a derailleur return springcompensator assembly 66. Derailleurs typically have a return spring. Theforce applied by that return spring is designed to work in conjunctionwith a set of gear shifters. However, if a dissimilar set of gearshifters is used, the return spring in the derailleur may be strongenough to move the gear shifter out of gear. The derailleur returnspring compensator assembly 66 is provided to stop this phenomenon fromhappening.

[0026] The derailleur return spring compensator assembly 66 is comprisedof a spring element 68 and a base bracket 69. The base bracket 69 ismounted to the frame of the bicycle a short distance from the cableadjustment compensator 60. The spring element 68 is engaged with one ofthe cable terminations 62. The spring element 68 biases the linkageelement 64 toward the gear shifter. As such, the derailleur returnspring compensator assembly 66 opposes any return spring that may bepresent within a particular derailleur assembly. In this manner, thereturn pull of a derailleur can be selectively corrected to match theneeds of a particular gear shifter assembly.

[0027] Referring to FIG. 4, another alternate embodiment of the presentinvention cable displacement compensation device 70 is shown. Thisalternate embodiment is similar to the embodiment previously shown anddescribed with reference to FIG. 2. However, in the shown embodimentelongated slots 72, 74 are formed on either side of the linkage element76. Cable terminations 78, 80 are provided at the ends of the cables.The cable terminations 78, 80 can engage the elongated slots 72, 74 atany point along the length of those slots. As such, the position of thecable terminations 78, 80 are infinitely adjustable along the length ofthe slots 72, 74. As such, the transfer in cable displacement created bythe device 70 can be finely adjusted if particularly finicky derailleurswith indexing shifters are used. Returning to FIG. 1, it will beunderstood that to use the present invention, shifter levers 12, 13 andderailleurs 14, 16 are provided on a bicycle 10. At least one cabledisplacement compensation 40 is then affixed to the frame of the bicycle10 in between the shifter levers 12, 13 and the derailleurs 14, 16. Atleast one cable from the gear shifter levers 12, 13 and at least onecable from the derailleurs 14, 16 are connected to the cabledisplacement compensation device 40. The point of attachment of thecables synchronizes the needed displacements between each gear shifterlever 12, 13 and each derailleur 14, 16. The proper positions can bedone via trial and error or through the use of printed instructions forknown brands of shifter levers and derailleurs.

[0028] It will be understood that the embodiments of the presentinvention device described and illustrated are merely exemplary and aperson skilled in the art can make many variations to the shownembodiment. All such alternate embodiments and modifications areintended to be included within the scope of the present invention asdefined below in the claims.

What is claimed is:
 1. A cable displacement compensation device,comprising: a pivot joint selectively attachable to the frame of abicycle; a linkage element coupled to said pivot joint, said linkageelement being free to rotate about said pivot joint, wherein a pluralityof cable attachment points are disposed on said linkage element atdifferent distances from said pivot joint.
 2. The device according toclaim 1, further including a plurality of cable terminations, whereinsaid cable terminations are used to terminate cables and join saidcables to said cable attachment points on said linkage element.
 3. Thedevice according to claim 1, further including a mechanical clamp forjoining said pivot joint to a bicycle.
 4. A bicycle assembly, including:a bicycle; a gear shift lever; a derailleur; a cable displacementcompensator disposed between said gear shift lever and said derailleur;a first cable running from said gear shift lever to said cabledisplacement compensator, wherein said first cable can be selectivelydisplaced by said gear shift lever; a second cable running from saidcable displacement compensator to said derailleur, wherein said cabledisplacement compensator transfers only a predetermined percentage ofsaid displacement of said first cable to said second cable.
 5. Theassembly according to claim 4, wherein said predetermined percentage isless than one hundred percent.
 6. The assembly according to claim 4,wherein said predetermined percentage is more than one hundred percent.7. The assembly according to claim 4, wherein said cable displacementcompensator, includes: a pivot joint selectively attachable to saidbicycle; a linkage element coupled to said pivot joint, said linkageelement being free to rotate about said pivot joint, wherein said firstcable and said second cable are attached to said linkage element atdifferent distances from said pivot.
 8. The assembly according to claim7, further including a plurality of cable terminations, wherein saidcable terminations are used to interconnect said first cable and saidsecond cable to said linkage element.
 9. The assembly according to claim7, further including a mechanical clamp for joining said pivot joint tosaid bicycle.
 10. A method of coordinating the cable displacementcreated by the gear shifter lever on a bicycle to the cable displacementrequired by a derailleur to properly shift gears, said method comprisingthe steps of: providing a cable displacement compensator; positioningsaid cable displacement compensator on a bicycle between a gear shifterlever and a derailleur; connecting said cable displacement compensatorto said gear shifter lever with a first cable; connecting said cabledisplacement compensator to said derailleur with a second cable, whereinsaid cable displacement compensator transfers predetermined partpercentage of cable movement from said first cable to said second cable.11. The method according to claim 10, wherein said step of providing acable displacement compensator includes providing a pivot joint and alinkage element that is free to rotate about said pivot joint.
 12. Themethod according to claim 11, wherein said step of positioning saidcable displacement compensator includes mounting said pivot joint to thebicycle in between said gear shifter lever and said derailleur.
 13. Themethod according to claim 11, wherein said step of connecting said cabledisplacement compensator to said gear shifter lever with a first cable,includes connecting said first cable to said linkage element at a firstdistance from said pivot joint.
 14. The method according to claim 13,wherein said step of connecting said cable displacement compensator tosaid derailleur with a second cable, includes connecting said secondcable to said linkage element at a second distance from said pivotjoint.
 15. The method according to claim 14, wherein said first distanceand said second distance are different.
 16. The method according toclaim 10, further including the steps of: providing a return springcompensator; connecting said return spring compensator to said cabledisplacement compensator, wherein said return spring compensator applieda predetermined bias to said second cable through said cabledisplacement compensator.